1. Field of the Invention
This invention relates to an air distribution system and in particular to an air distribution system for a vehicle cab.
2. Description of the Prior Art
Various types of air distribution systems are presently available which utilize a single blower to draw air into and circulate it throughout a vehicle cab. Such systems work sufficiently well until the upstream air filter becomes clogged with dirt and dust. When this occurs, the system is no longer able to draw in fresh outside air and therefore starts to recirculate the stale inside air. By recirculating the stale inside air, two undesirable circumstances occur. First, the air pressure within the cab decreases to the point where dusty outside air is able to penetrate through the many small unsealed openings of the cab. This creates a very unpleasant environment for the operator because the incoming air has not been filtered or temperature treated. Secondly, the stale air within the cab is never exchanged with fresh outside air. This problem becomes acute if the operator is smoking, since the smoke-filled air is merely recirculated, thereby creating a haze within the cab.
These disadvantages are overcome by the present invention wherein a two-blower air distribution system is taught. A first constant-volume blower assures a constant amount of fresh incoming air, while a second, variable-speed blower controls the air circulation within the vehicle cab.
The general object of this invention is to provide an air distribution system for a vehicle cab. A more specific object of this invention is to provide an air distribution system for a vehicle cab which will allow for constant cab pressurization but still permit the operator to vary the air flow within the cab.
Another object of this invention is to provide a two-blower system wherein a first constant-volume blower draws in fresh outside air in order to maintain a constant cab pressurization while a second variable-speed blower controls the air circulation within the cab.
Still another object of this invention is to provide an air distribution system wherein the structural members of the cab serve as conduits for routing the outside air into the cab.
Still further, an object of this invention is to provide an air distribution system wherein the two blowers and a temperature controller are positioned on the floor of the cab, rather than in a roof member, so as to lower the center of gravity of the cab and therefore improve the ride characteristics of the vehicle.
Other objects and advantages of this invention will become apparent to one skilled in the art based upon the ensuing description.